Purpose: Acute bouts of exercise reduce postprandial triacylglycerol concentrations ([TAG]) in healthy boys and girls; however, it is not known whether this effect is mediated by the energy deficit. This study examined whether the exercise-induced reduction in postprandial [TAG] persists after immediate dietary replacement of the exercise energy expenditure (EE). Methods: Eighteen healthy 11- to 13-year-old boys (mean(SD): body mass 41.3(8.4) kg;
peak oxygen uptake ( VO 2) 55(5) mL·kg-1·min-1) completed three, 2-day conditions in a within-measures, crossover design separated by 14 days. On day 1, participants rested (CON), exercised at 60% peak VO 2 inducing a net EE of 32 kJ·kg-1 body mass (EX-DEF) or completed the same exercise with the net EE replaced immediately (EX-REP). On day 2, capillary blood samples were taken in the fasted state and at pre-determined intervals throughout the 6.5 h postprandial period. A standardised breakfast and lunch meal were consumed immediately and 4 h, respectively, after the fasting sample. Results: Based on ratios of the geometric means (95% confidence intervals (CI) for ratios), EX-DEF fasting [TAG] was 19% and 15% lower than CON (-32 to -4%, ES = 1.15, P = 0.02) and EX-REP (-29 to 0%, ES = 0.91, P = 0.05) respectively; CON and EX-REP were similar (-4%; P = 0.59). The EX-DEF total area under the [TAG] versus time curve was 15% and 16% lower than CON (-27 to 0%, ES = 0.55, P = 0.05) and EX-REP (-29 to -2%, ES = 0.62, P = 0.03)
respectively; CON and EX-REP were not different (2%; -13 to 20%, P = 0.80). Conclusion: Immediate replacement of the exercise-induced energy deficit negates the reduction in postprandial [TAG] in boys; this highlights the importance of maintaining a negative energy balance immediately post-exercise to maximise the metabolic health benefits of exercise.

Description:

This paper was accepted for publication in the journal Metabolism: clinical and experimental and the definitive published version is available at http://dx.doi.org/10.1016/j.metabol.2015.12.001

Sponsor:

The research was supported by the National Institute for Health Research (NIHR) Diet, Lifestyle & Physical Activity Biomedical Research Unit based at University Hospitals of Leicester and Loughborough University. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.